The present invention relates to a tool for fitting a belt into the groove of a pulley. It applies more particularly to power transmission belts and more particularly to the motor vehicle field, to the household electrical goods field and to industry.
The Applicant Company markets, in particular as a belt intended for the driving of motor-vehicle accessories (alternator, air conditioning, etc.), a belt that it is possible to fit by stretching and which, after fitting in a transmission system, maintains sufficient tension throughout the lifetime of the belt, without there being any need to tension it by means of a fixed tensioner.
The fitting of this belt (of the so-called “snap-on” type) involves high stresses and it is generally carried out using a fitting tool, whether this be in the factory (“first fitting”) or as a replacement.
Fitting tools are already known which involve having a part of the tool in contact with the bottom of the groove of the pulley. Such tools are in particular described in the American patents U.S. Pat. No. 3,138,963 (PRINCE), U.S. Pat. No. 4,111,063 (JOURNEY) and U.S. Pat. No. 4,109,544 (CLARK).
The disadvantage of these devices is that they are suitable only for belts transmitting low powers, because they come directly into contact with the groove of the pulley which they risk damaging.
This risk is even higher for motor vehicle belts (in general of the K type) which have a plurality of serrations to which correspond the complementary profiles of the bottoms of the pulley grooves.
Another fitting tool, of the lever type, has been proposed in the patent U.S. Pat. No. 5,653,654 (DAVIS). It comprises two fingers 20 and 21 forming a lever. In order to use it, it is necessary in advance to slacken the tension of the belt, which is not compatible with a belt of the “snap-on” type for which the transmission system is rightly deprived of a tensioner allowing such an operation.
Other belt tensioners more particularly intended for belts of this type have been proposed for motor vehicle applications. In particular, reference will be made to the European Patent EP 831 247. This type of tool is applied to the cheek and the edge of the pulley.
This has several consequences:
on the one hand, the shape of the tool is relatively complicated,
on the other hand, the curvature of the tool is defined by the curvature of the pulley, which means that there are necessarily as many patterns of tools as there are diameters of pulleys,
and, finally, because of its position, the tool occupies a non-negligible lateral space.